1. Field of the Invention
The present invention relates to a fan having a function for detecting a fault in the fan.
2. Description of the Related Art
In the prior art, in order to detect various faults, in fans, such as the breakage and the loss of a rotating part such as a vane of the fan and/or stoppage and deceleration of the rotation of the fan, various methods, utilizing light, magnetism, ultrasound or air pressure, or monitoring the current through the motor of the fan, have been developed. For example, Japanese Unexamined Patent Publication No. 2003-307194 discloses a device, for detecting an abnormal rotational speed of a fan, having a function for outputting a pulse signal synchronized with a period of a current. This device judges the deceleration of the rotational speed when a period of the pulse signal becomes longer.
Any of the above methods utilizing light, magnetism, ultrasound or air pressure cannot be used, depending on a type and/or an operating condition of a fan to be detected. Further, in a method using a pulse signal as described in Japanese Unexamined Patent Publication No. 2003-307194, a breakage and a loss of a vane of a fan cannot be detected. Therefore, such a fault must be found by a visual inspection.